Given a new mayor who catapulted into office by castigating the police, given a City Council that passed two punitive bills related to the police and racial profiling, given the prospect of federal oversight on stop-and-frisk, given the overshadowing of the stunning drop in crime by the open sore of racial insensitivity, New York police may decide to engage in, as police call it, de-policing.

If morale sinks too low, one former New York City police official suggests, officers may not go after criminals “in the most aggressive fashion.”

“Right now, police in New York are not happy,” the new commissioner conceded in his conference room at police headquarters Friday evening, surrounded by walls of video screens tracking crime around the city. “They’re frustrated because their good work really did get banged around in the campaign.”

There was a record decline in crime and a record increase in tourism, Bratton said, and “cops aren’t feeling the residual benefit of that.”

He said “the most angst” was being caused by a City Council bill expanding the ability to sue over racial profiling by officers, because police see it as a risk to themselves and their families.

He said New York has “a crisis of confidence on the part of the cops about what it is that we can do” and “a crisis of confidence in the public about what the cops have been doing.”

Bratton, always very popular with the police who work for him, has been through it before. When he went to head the L.A. force in 2002, he said, police were so demoralized by cascading troubles and bad leadership that some sank into a “drive by and wave” mode.

While diplomatically praising his old rival Ray Kelly, Bratton also noted that there were missed opportunities to curb stop-and-frisk.

“The shame of it,” he said, “is it probably could have been addressed a year or two years ago but for the intransigence of Mayor Bloomberg. I hesitate to describe it as intransigence because I really do believe that both Mayor Bloomberg and Commissioner Kelly, both good men, both committed to keeping this city safe, really deeply believed that the reason crime was going down, the reason there was less gun violence, the reason there were fewer guns being taken off the street, was because of the increasing numbers of stop-question-frisk.

“And eventually because of that unwillingness to step back from that posture, it became a rallying cry for a number of the mayoral candidates, including Mayor de Blasio, who was able to most successfully use it as a platform.”

Police, he said, “need clear guidelines, clear guardrails, and we don’t have that right now.” They are comfortable re-engaging, he said, when they have those guardrails.

In Bloomberg’s final years as mayor, Bratton said, “Cops themselves felt that they were in a no-win position. They had an administration, Mayor Bloomberg, Commissioner Kelly, who were demanding more and more and more. And the cops themselves felt, you know, it’s too much. And the community was saying it’s too much. It’s like a doctor giving too much chemotherapy: ‘Doctor I’m feeling better but you’re giving me all this chemo and I’m feeling worse again.’ ”

In L.A. in 2002, Bratton faced a crisis where morale was low after a corruption scandal and after the city was crowned the murder capital of America, and an inspector general was on hand for oversight. “We got the cops out of their cars,” he said. “They got back to making arrests. They got back to doing stop-question-frisk. But they were also doing it in a way that was focused.”

His initiatives focusing on gangs and crime data, he asserted, allowed the police an appropriate structure “so that every black kid that was wearing a long white T-shirt with shorts wasn’t thought of as a potential suspect.”

The last time Bill Bratton became police commissioner of New York, in 1994, his mission was to take back the city. Now his mission is to back off — to rein in the force enough so that minorities do not feel hounded. The last time he was Top Cop, his boss was Mr. Law and Order, and Bratton was the tip of Rudy Giuliani’s spear. This time, he’s working for a liberal populist mayor who got elected thrashing the excesses of stop-and-frisk, and he’s supervising police officers who are trepidatious about working for a man who won office by stoking the fires of public opinion against them. (Dante de Blasio did a potent ad for his father noting that he might be a likely candidate for stop-and-frisk.)

Trying to help Christine Quinn (tepidly) and stop de Blasio during the mayoral primary, Michael Bloomberg’s aides fed the paranoia that under de Blasio, New York would flame into “Bonfire of the Vanities.” Bratton must be the affirmative answer to all the jittery New Yorkers asking “Is it safe?,” fearing that fiends are going to start climbing out of manholes if the new mayor goes all flower power on crime. And he must be the affirmative answer to the minority community’s demand for more sensitivity.

After 20 years of news conferences touting crime declines and a safer city, if crime stops going down — let alone if it goes up — it will be a political catastrophe for City Hall.

Even for a master at shaping perception like Bratton, it’s going to require exquisite balance. Skeptics on both sides of the spectrum, from Al Sharpton to former Mayor Bloomberg, suggest the changes on stop-and-frisk may be cosmetic.

On the eve of leaving office, Bloomberg, defensive about the scar on his legacy, noted to Capital New York that in L.A. Bratton — considered the godfather of the sort of aggressive policing tools that have come under fire — was just as much a proponent of stop-and-frisk as Kelly was. “Bratton did more stop and frisks per capita than Kelly did,” Bloomberg said. “They’ll call it ‘frisk and stop’ instead of stop-and-frisk.”

Bratton mulled that his specialty had been coming in to lead police departments “in total crisis” and, in a way, he violated his own philosophy by following someone so successful.

But he believes he can resolve the problems with stop-and-frisk and shaky morale. “I didn’t come back to New York to fail,” he said flatly, dapper as ever in a Hermès tie with elephants and a blue Rolex watch his wife gave him.

Bratton said he wants to bring in a language expert, as he did back in 1994, to train police on the best ways to use language to “calm down incidents” by being respectful rather than ratchet them up by being confrontational.

Noting that you have to use stop-and-frisk “with skill,” he said: “We have an expression in policing that it’s not the use of force that gets cops in trouble, it’s the use of language.”

He said an officer who says, “Sir, can I speak to you?,” rather than “Hey, you, get over here,” will be more productive. They also need exit strategies, he said, to depart from encounters without “demeaning” people.

He knows he has a super-healthy ego but says it just reflects confidence. He notes that his famously fractious relationship with Giuliani — Rudy grew envious of Bratton’s glowing press as “America’s Top Cop” and forced him out — taught him a good lesson. He plans to meet with Mayor de Blasio once a week — “no matter what” — to encourage transparency, so that gossip doesn’t “fester.”

He said everything was going well so far, even though they are only on the third day of their relationship.

His experience with Rudy and two mayors in L.A. has taught him this: “You’ve got to keep them informed. Try to have no surprises, if you will.”

With that, he headed off through the snowy streets for a meeting with the mayor.

Correction:

An earlier version of the photo caption that accompanied this column misstated the day that William J. Bratton was sworn in. It was on Thursday, not Tuesday.